Kernel Estimate for the Intensity Function

To anyone who can help me:
I found that the function "smooth.ppp" in the package "spatstat" provides 
the kernel estimate for the intensity function of a "two-dimensional" point 
process with marks.
Does anyone know that which package can do this for simply a "one-
dimensional" point process with marks?
I've been searching all over the R site but still can not find the packages.
Thanks a lot.

Ying-Chao Hung